Hello DJI team,

Could someone please help me locate / highlight the text in the user manual that talks about the Spark shooting upward by 10 meters when the RTH function activates (due to low battery). I'm trying to make the point that this was a product malfunction. When I spoke to your team, your repair technician could not find this behavior explained in the user manual, and promised to call me back. However, I have not heard back for a week. Please note the obstacle avoidance was not enabled, therefore the unit should not have gone 10 meters up to avoid any given obstacle. My case number is CAS-1019265-N4P5C1. All these details were recorded through the DJI app, and can provide screenshots of everything, please review my case. I would love to have my drone repaired (per your policy), or have my money refunded if possible.

Thank you,
Tony

It is probably not related to the obstacle avoidance in your case but to your RTH settings. Check the value you have there for RTH altitude, default is 30 meters. If the setting "RTH at current altitude" is not enabled (default setting), the Spark will always first go to the RTH altitude value before returning. If "RTH at current altitude" is enabled, it will do exactly that and not change altitude first.

Sir, per the case log, our colleagues have contacted you and explained the accident. Please check below:

The user was flying the drone until it had low power, the drone triggered auto RTH, user was flying under a tree at the same time, so the drone crashed into the tree during the rise up process of RTH. In the app you can clearly see a default setting for RTH altitude.

For more details of RTH, please check the User Manual. From all the data we collected, it was confirmed as pilot error. We are sorry we can not offer you the warranty service. Our colleagues has offered you the best discount according to DJI's policy, please let us know how would you like to proceed.

Wachtberger Posted at 2017-9-28 22:17
It is probably not related to the obstacle avoidance in your case but to your RTH settings. Check the value you have there for RTH altitude, default is 30 meters. If the setting "RTH at current altitude" is not enabled (default setting), the Spark will always first go to the RTH altitude value before returning. If "RTH at current altitude" is enabled, it will do exactly that and not change altitude first.

Hi Wachtberget,

Thank you so much for responding, much appreciated!

I have my "RTH at Current Altitude" disabled, and "Return to home altitude" set to 0, wouldnt that mean that it should have landed right where it was, instead of shooting up? I dont see anywhere a default of 30 meters.
Thank you so much for your input

Cheers,
Tony

DJI Susan Posted at 2017-9-29 22:46
Sir, per the case log, our colleagues have contacted you and explained the accident. Please check below:

The user was flying the drone until it had low power, the drone triggered auto RTH, user was flying under a tree at the same time, so the drone crashed into the tree during the rise up process of RTH. In the app you can clearly see a default setting for RTH altitude.

Hi Susan,

Thank you for quick response! I did not receive a follow up call after speaking with Tom, but I'm glad everything was documented, thank you!

Thank you for highlighting the expected behavior from the user manual, I checked the fail safe altitude (assuming it is "Return to home Altitude", please correct me if I'm wrong) and it is set to 0. With that setting set the way it is, wouldn't an increase in altitude upon the RTH being triggered be a software malfunction?

Thank you for helping me look into this

Cheers,
Tony

TOrto Posted at 2017-9-30 10:50
Hi Susan,

Thank you for quick response! I did not receive a follow up call after speaking with Tom, but I'm glad everything was documented, thank you!

You cannot set RTH to land, the only time it will land is when critical battery and it doesn’t have enough power to go home, you also cannot set RTH to 0 you must set RTH between 20_50  metres if you try to set to 0 it will revert to whatever number you had set before trying to set it to 0. Your minimum must be 20 metres. So your aircraft behaved correctly by ascending.
Sorry about your crash but this is the case.

TOrto Posted at 2017-9-30 10:32
Hi Wachtberget,

Thank you so much for responding, much appreciated!

I can only second what has been explained already here above. Nevertheless I am sorry for your crash.

To clarify:
If RTH is triggered within 3 metres of the home point - it will land.
If triggered from 3-20m from the homepoint it will land if RTH has fly back at same altitude disabled. If enabled it will return to home at the current altitude (minimum 2.5m) with the OA engaged at 6.7MPH - ideal if over a lake in front of you. If 20-100m away it will fly back at 6.7mph with the OA engaged at the height set to RTH in the app (minimum 20m high) whether fly back at same altitude is enabled or not. If more than 100m away, it will return at 22MPH with the OA DISengaged at the preset height again, minimum 20m.
If you lose signal flying underneath anything the drone will fly up into it as it attempts to reach the set altitiude to avoid obstacles in front of it on the autonomous return - only the Inspire 2 has an upward obstacle avoidance sensor.
That is why you should never fly under bridges or trees at distances of more than 20m away where the signal may be lost or if running on a low battery - especially with a drone that uses WiFi as its transmission and has a 10-15 minute flight time. Setting RTH to 0 would stop it from returning anywhere so will not work...
The option to set failsafe to hover or land is in the Mavic and Phantom 4 series but not the Spark which is why it has a broader range of RTH actions for different scenarios based purely on the distance from the home point - as detailed in the manual!

hallmark007 Posted at 2017-9-30 13:29
You cannot set RTH to land, the only time it will land is when critical battery and it doesn’t have enough power to go home, you also cannot set RTH to 0 you must set RTH between 20_50  metres if you try to set to 0 it will revert to whatever number you had set before trying to set it to 0. Your minimum must be 20 metres. So your aircraft behaved correctly by ascending.
Sorry about your crash but this is the case.

Thank you so much for your reply Hallmark007 (and expressing sympathy ) !

The RTH in my app was pre-set to "0". I have never attempted to change the RTH, and shows '0' in my settings (as the screenshot shows) :/

Wachtberger Posted at 2017-9-30 13:43
I can only second what has been explained already here above. Nevertheless I am sorry for your crash.

Thanks Wachtberger!!

ACW Posted at 2017-9-30 13:52
To clarify:
If RTH is triggered within 3 metres of the home point - it will land.
If triggered from 3-20m from the homepoint it will land if RTH has fly back at same altitude disabled. If enabled it will return to home at the current altitude (minimum 2.5m) with the OA engaged at 6.7MPH - ideal if over a lake in front of you. If 20-100m away it will fly back at 6.7mph with the OA engaged at the height set to RTH in the app (minimum 20m high) whether fly back at same altitude is enabled or not. If more than 100m away, it will return at 22MPH with the OA DISengaged at the preset height again, minimum 20m.

Thank you so much for your response ACW!

My app had RTH pre-set to "0", I'm thinking that could be the source of the problem itself. Sounds like many of you have other drones (mavics, phantoms, etc.) and these come with other defaulted settings.

If all spark users have that set to 0, it could cause problems for them too, and hope DJI takes action on that before more units continue crashing ( it will not be good for their business ) And if this is unique to my unit I hope they honor their policy and repair my drone under warranty!

Either way, thank you again for commenting!

Cheers,
Tony

TOrto Posted at 2017-9-30 21:28
Thank you so much for your response ACW!

My app had RTH pre-set to "0", I'm thinking that could be the source of the problem itself. Sounds like many of you have other drones (mavics, phantoms, etc.) and these come with other defaulted settings.

I have once tried to set the RTH altitude to 10 meters and the App did not accept to go below 20 meters. The fact that yours accepted the value 0 is quite astonishing indeed. When you send in your Spark, DJI might be able to find out what went wrong.

TOrto Posted at 2017-9-30 10:50
Hi Susan,

Thank you for quick response! I did not receive a follow up call after speaking with Tom, but I'm glad everything was documented, thank you!

After reading this, first of all I am sorry for your crash... Please note that your Go 4 App will not show you the RTH altitude that is set on your aircraft unless the aircraft is turned on and connected. All my DJI aircraft will show the setting at "0" until you turn them on and connect to the App. IMO this is because DJI has many drones that populate these forms inside the App and it is waiting to see which drone is connected. The drone hardware will keep the last setting stored onboard until you change it. I have my Spark, Mavic, Phantom and Inspire all set up differently.

Rich

Spark turned on and Go 4 App connected at my computer:


Spark turned off and restart the App:

TOrto Posted at 2017-9-30 21:28
Thank you so much for your response ACW!

My app had RTH pre-set to "0", I'm thinking that could be the source of the problem itself. Sounds like many of you have other drones (mavics, phantoms, etc.) and these come with other defaulted settings.

The principle of RTH works the same on all DJI drones. When yours lost signal whilst under a tree (the tree probably being the obstruction that caused the signal loss) or hit low battery RTH which you obviously didn't cancel on the ten second countdown it would have initiated RTH and it is perfectly correct for the drone to immediately ascend to the preset altitude before forward flight. You can not set RTH to 0 - you should ALWAYS check the RTH setting in the app as part of your preflight checks and I'm sure it would have shown either 30m or 20m with the Spark turned on. If it showed '0' then you should not have taken off as clearly a faulty drone. Again, I am sorry for your loss but this is a classic pilot error in the drone community and one of the main reasons drones crash. What RTH altitude popped up in the green box immeidately after take off? The app even tells you this with audible confirmation too and it will be in the flight records.

hallmark007 Posted at 2017-9-30 13:29
You cannot set RTH to land, the only time it will land is when critical battery and it doesn’t have enough power to go home, you also cannot set RTH to 0 you must set RTH between 20_50  metres if you try to set to 0 it will revert to whatever number you had set before trying to set it to 0. Your minimum must be 20 metres. So your aircraft behaved correctly by ascending.
Sorry about your crash but this is the case.

your explanation is clearly saying that it is bad software programing.
if we cant set the RTH to 0m, why is the go 4 app accepting 0m as a preset ?
To me it looks like it is a dji warranty thing and at the same time a push for a go4 update programing.

To OP:
If flying under something, always cancel the RTH before it kicks in.
That is my main rule anyway. Batterie is a info, not a RTH reason
You can always fly home quicker as the RTH will be able to do it

TOrto Posted at 2017-9-30 21:10
Thank you so much for your reply Hallmark007 (and expressing sympathy  ) !

The RTH in my app was pre-set to "0". I have never attempted to change the RTH, and shows '0' in my settings (as the screenshot shows) :/

Hey TOrto, I’m not sure if it is set to 0 when your spark was turned on, I can only tell you what happens in mine when my spark is turned on.
If I try to set to 0 it reverts to 30 metres my last setting, in fact if I try to set to anything less than 20 metres it will continue to revert to 30 metres, I can choose any number between 20/50 metres and it will set.
I use iOS iPhone 7.

If your default is set at 0 when spark is turned on then is a bit strange, but as ACW said it’s really something you should check preflight, maybe you can throw a bit more light on this. It will be dji’s decision ultimately, but if what you say is what happened then some explanation should be given regards to this matter.

S-e-ven Posted at 2017-9-30 23:07
your explanation is clearly saying that it is bad software programing.
if we cant set the RTH to 0m, why is the go 4 app accepting 0m as a preset ?
To me it looks like it is a dji warranty thing and at the same time a push for a go4 update programing.

I’m not saying anything about software, I have laid out how my RTH works and what it clearly says in your manual, that default RTH is 30 metres and if I try to input any number below 20 metres while the Aircraft is turned on it will revert back to default 30 metres.
If your RTH can be set at 0 while turned on then maybe you could put up a small video of you setting RTH to 0 go back out of RTH setting back in and see if it’s still at 0..

I think you will clearly see screenshot of 0 setting Aircraft is turned off.

We also need to check our RTH setting preflight it is probably one setting that will save your Aircraft so it’s pretty important.

I agree, it is one of the importants settings to check pre flight.
My statement b/c of a software issue based on the pictures, OP postet.
If he cant set it on 0, if connected to the Spark, it is not an issue.
But if he could set it to 0m as it is to see on the picture, and this stands with the drone connected, it is a DJI problem, methinks.
And then it doesnt matter if manual says you cant.
I have not checked this 'cause I cancel RTH mostly, or switch it to current altitude, if flying under trees, p.ex.
And cancel the RTH then there even quicker.
But in case we all cant set the altitude to 0m, forget about my posts in this topic, please ;-)

S-e-ven Posted at 2017-10-1 03:31
I agree, it is one of the importants settings to check pre flight.
My statement b/c of a software issue based on the pictures, OP postet.
If he cant set it on 0, if connected to the Spark, it is not an issue.

I fully agree the manual clearly states RTH default set at 30 metres, if this is not the case then it’s more of a problem for dji than OP. So your posts are relevant.

TOrto Posted at 2017-9-30 10:50
Hi Susan,

Thank you for quick response! I did not receive a follow up call after speaking with Tom, but I'm glad everything was documented, thank you!

Thanks for getting back to us. As hallmark007 mentioned, the RTH altitude can not be set as 0. You will see the right RTH altitude when connecting the aircraft. It seems that you didn't connect it. The preset altitude is 30m, instead of 0.

S-e-ven Posted at 2017-10-1 03:31
I agree, it is one of the importants settings to check pre flight.
My statement b/c of a software issue based on the pictures, OP postet.
If he cant set it on 0, if connected to the Spark, it is not an issue.

Sir, the altitude can not be set as 0. The 0 only appears when the pilot do not connect the aircraft as the data was written in the Main Control.

DJI Susan Posted at 2017-10-10 23:38
Sir, the altitude can not be set as 0. The 0 only appears when the pilot do not connect the aircraft as the data was written in the Main Control.

Yes, thank you!